1. Field of the Invention
The present invention relates generally to magnetic tape drives, and more specifically to a method for locating individual blocks of data on magnetic tapes.
2. Background of the Invention
Magnetic tape is a sequential storage medium used for data collection, backup, and historical purposes. Magnetic tape is made of flexible plastic with one side coated with a ferromagnetic material. Magnetic tapes come in reels and cartridges of many sizes and shapes. In older systems, open reels are used while most presently available systems employ cartridges to hold the magnetic tape.
For information storage and retrieval, magnetic tape has proven especially reliable, cost efficient and easy to use. In an effort to make magnetic tape even more useful and cost effective, attempts have been made to store more information per given width and length of tape. This increase in storage has generally been accomplished by including more data tracks on a given width of tape. While allowing more data to be stored, this increase in the number of data tracks results in those tracks being more densely packed onto the tape.
When using a high efficiency modulation coding technique for writing data to tape, the codes tend to be unidirectional in nature. In a tape drive environment, the restriction of reading in only one direction can cause severe performance degradation when searching for individual blocks of data or searching for the next write position.
Therefore, it would be beneficial to have an asynchronous method to locate individual blocks of data, without having to read the unidirectional blocks of data.